Southern Great Plains

Food, Energy, and Water Resources

Quality of life in the region will be compromised as increasing population, the migration of individuals from rural to urban locations, and a changing climate redistribute demand at the intersection of food consumption, energy production, and water resources. A growing number of adaptation strategies, improved climate services, and early warning decision support systems will more effectively manage the complex regional, national, and transnational issues associated with food, energy, and water.

Food, energy, and water systems are inseparable. Any change in demand for one will impact demand on the other two. The quality of life of the 34 million people residing in the Southern Great Plains is dependent upon the resources and natural systems for the sustainable provision of food, energy, and water. At least 60% of the region’s population is clustered around urban centers, which are experiencing population growth that exceeds that of rural communities. The remaining population is spread across vast areas of rural land.14,30,31,32,33 As the population in the region grows, rapid urbanization and economic development opportunities will drive an increase in the demand for food, energy, and water. Water is used in every aspect of agricultural production and electricity generation. Energy is required to extract and deliver water of sufficient quality for diverse human and agricultural use, as well as healthy consumption and wastewater treatment. Both water and energy are required to irrigate and process agricultural products and livestock to feed the region’s increasing population. The complex interdependencies at the food–energy–water nexus create enormous challenges.

When severe drought affected the Southern Great Plains in 2011, limited water availability constrained the operation of some power plants and other energy production activities. Contention for water developed between consumers associated with the food–energy–water nexus. The recent boom in domestic unconventional oil and gas development brought on by hydraulic fracturing and horizontal drilling represents another stressor to this nexus. This development has added complexity to the regional dialog about the relationship between food, energy, and water resources.

Figure 23.5: The photo shows the drought impact on a stock pond near Kurten, Texas, in 2011. Photo credit: John …

Superimposed on the existing complexities at the intersection of food, energy, and water is the specter of climate change. During 2010–2015, the multiyear regional drought severely affected both agricultural and aquatic ecosystems. One prominent impact was a reduction of irrigation water released for the Texas Rice Belt farmers on the Texas coastal plains, as well as a reduction in the amount of water available to meet instream flow needs in the Colorado River and freshwater inflow needs to Matagorda Bay. The Lower Colorado River Authority (LCRA), through its Water Management Plan (WMP), balances the needs of competing water demands in the Lower Colorado River Basin of Texas. Depending upon the amount of water stored in lakes, the WMP requires that LCRA reduce or cut off interruptible stored water for most downstream agriculture so firm water supplies are available to meet the basic needs of cities, businesses, and industries during drought.

In one year, planted acres of rice in Matagorda County, Texas, dropped from 22,000 acres to 2,100 acres.34 The ripple effect on the local economy was severe, with a 70% decline in sales of farm implements and machinery. Some family-owned establishments that had survived for decades closed permanently.35 Irrigation strategies shifted from river-based to pumping water from the Gulf Coast Aquifer, and dozens of new wells were drilled. Drilling water wells then resulted in declining groundwater levels, adding stress to water levels that had historically been falling in the region.36 Some farmers attempted to adapt by making the difficult transition to other crops such as corn. However, when flooding rains inundated the region in 2016, 15% of the corn crop was swept away in flood waters.37 Thus the 2010–2015 drought simultaneously affected agriculture, energy, recreation, and economic activity, eventually leading to increased groundwater development and potential future overexploitation. Projected increases in drought duration and severity imply even more pervasive direct and indirect effects. These impacts might have been even more severe had it not been for adaptation actions taken by the City of Austin, including implementation of drought contingency plans and water-use cutbacks in coordination with the City Council and community.

Climate change has significant negative impacts on agriculture in the United States, causing substantial economic costs (Ch. 10: Ag & Rural).38,39 The effects of drought and other occurrences of extreme weather outside the Southern Great Plains also affect the food–energy–water nexus in the region. The neighboring Southwest region is especially vulnerable to climate change due to its rapidly increasing population, changing land use and land cover, limited water supplies, and long-term drought (Ch. 25: Southwest).40 States in the Southern Great Plains import over 20% of their food-related items from Arizona, and El Paso, Texas, receives 25% of its consumable foods (mostly vegetables) and 18% of its animal feed supplies from Arizona.41 In addition, relationships across the border of the Southern Great Plains with Mexico will be critical to a better understanding of the food–energy–water nexus (see Case Study “Rio Grande Valley and Transboundary Issues”) (see also Ch. 16: International, KM 4).

Case Study: Rio Grande Valley and Transboundary Issues

In the U.S.–Mexico transboundary region of the Southern Great Plains, no hydrologic resource is more critical than the Rio Grande and its attendant tributaries. Partnered, binational management of the basin’s water supply is essential to supporting the agricultural, industrial, and community infrastructure in place along the Rio Grande valley. Proactive and collaborative water management strategies allow for effective flood control, mitigation of drought impacts, and maximization of water quality, among other benefits.42

The Rio Grande is highly sensitive to variations and changes in the climate of the Southern Great Plains, where changes can have marked impacts on the valley’s extensive agricultural productivity.43,44 Increasing regional temperatures,45 consistent with global trends, will enhance the severity of drought impacts via the acceleration of surface water loss driven by evaporation, particularly in large Rio Grande reservoirs such as Lake Amistad. Changes in regional precipitation patterns, including observed increases in extreme rainfall events as part of a regional “dipole” dry-wet-dry-again pattern,10 will affect both drought and flood occurrence and intensity along the Rio Grande channel. Other climate-driven impacts, such as changes in wildfire frequency46 and increased vulnerability to heat events,40 will further challenge the preparedness and resilience of communities on both sides of the border.

A growing number of adaptation strategies47 and an increasing provision of regional climate services in the Southern Great Plains48 bode well for an improved future ability to effectively manage the Rio Grande’s transboundary water interests. This is particularly true in the context of early warning decision support systems. Frequently, extreme weather and climate events, such as the 2011–2012 La Niña and 2015–2016 El Niño episodes, serve as catalyzing opportunities to develop new and refine existing information delivery pathways from climate services providers to stakeholder audiences. One recent application in the Rio Grande transboundary region is bilingual seasonal climate outlooks and impact assessments,49 which are utilized by stakeholders to strengthen regional drought and wildfire outlooks46 and which augment other ongoing efforts to strengthen bilingual climate services delivery.50

The 2017 Texas State Water Plan52 indicates that the growing Texas population will result in a 17% increase in water demand in the state over the next 50 years. This increase is projected to be primarily associated with municipal use, manufacturing, and power generation, owing to the projections of population increase in the region. Likewise, the Oklahoma Water Plan indicates that water use projections in Oklahoma are expected to increase by 21% for municipal use, 22% for agricultural use, and 63% for energy use.53 The Kansas Water Plan’s preliminary assessment of projected water demand in Kansas also shows an increase of 20%, but with the expected variability depending upon rural versus urban areas.54 Throughout much of western Kansas, western Oklahoma, and the Texas Panhandle, groundwater from the Ogallala Aquifer is the dominant water source,17,55 benefitting the agricultural sector in particular. This resource is known to be shrinking faster than it is replenishing, and some portions are likely to become an insufficient source or become completely depleted within the next 25 years, particularly at its southernmost extent.17 Drought more persistent than that experienced in the region’s recent history would trigger large social and economic consequences, including shifting agriculture, migration, rising commodity prices, and rising utility costs.20

The importance of groundwater as a resource will increase under a changing climate as the intensification of hydrologic extremes decreases the reliability of precipitation, soil moisture, and surface water, and as surface water supplies are becoming increasingly over-allocated.56,57,58

Research into the food–energy–water nexus is in its early stages and historically tends to examine only one or two components.59,60,61,62,63,64,65 It is clear that tradeoffs and cascading complexities exist between sectors, and changes in one sector are likely to propagate through the entire system (Ch. 17: Complex Systems). There are significant gaps in the scientific understanding regarding the role that climate change will play as a disruptive force and a threat to food, energy, and water security.60,63,66,67,68

Case Study: The Edwards Aquifer

The Edwards Aquifer is a “karst” aquifer, composed of limestone and characterized by solution features such as large pores, caves, sinkholes, and conduits that channel groundwater flow. The Edwards provides groundwater to the central Texas region. It serves more than two million people, including the cities of San Antonio, San Marcos, and Austin, which are three of the fastest-growing cities in the country.69 The aquifer is a source of water for drinking, industry, agriculture, livestock, and recreation. In particular, San Antonio relies nearly entirely on the Edwards for its drinking water. The aquifer is also a habitat for a number of endemic and endangered species. As a shallow karst aquifer, the Edwards is especially sensitive to climate change. Its shallow depth and karst features allow for rapid infiltration and recharge during wet periods, and discharge is similarly responsive, making the Edwards vulnerable to climate extremes of droughts and floods. This high susceptibility and exposure to climate change is a major challenge for managing the Edwards Aquifer as a resource.70 The probable impacts of climate change for the Edwards Aquifer include a decrease of water supply during droughts, a degradation of habitat for species of concern, economic effects, and the interconnectivity of these impacts. These climate change impacts will be exacerbated in central Texas’s rapidly urbanizing regions, as increasing impervious cover will affect water quality and rates of runoff and recharge.

Water availability and demand: The population of Texas is projected to grow by more than 70% between 2020 and 2070, with the majority of the increase projected to occur in urban centers.52 Increased demand for water will come from municipal, power generation, agriculture, manufacturing, and livestock uses.52 Over this same period, water availability in the U.S. Southwest is projected to decrease due to a shift to a more drought-prone climate state.28,71 History shows that increases in population and pumpage from the Edwards led to unsustainable use of water from the aquifer during the drought of the 1950s.72 The lessons learned from the 1950s drought and the more intense 2011 drought provide a well-suited application for models of how the aquifer and associated ecosystems will respond to further climate change.73

Habitat: Plants and animals are sensitive to a variety of changes related to the Edwards Aquifer groundwater system, including changes in habitat, water levels, spring flows, and water quality. An example of the last is an analysis of dissolved oxygen concentrations (DO) in water in Barton Springs, a major point of discharge from the Edwards Aquifer. Most notable are water quality effects on the Barton Springs salamander (Eurycea sosorum), a federally listed endangered species native to these springs. An analysis of DO, discharge, and temperature measurements at the springs indicates that low DO episodes that correspond to salamander mortality could result from 1) lower discharge from the springs resulting from increased water withdrawals or decreased recharge as a result of drought, and/or 2) increased water temperature as a result of climate change.74 A key challenge is understanding and modeling the extent to which endangered and native species can be protected in their habitats associated with the aquifer.73,75,76

Impacts: Dramatic drawdowns of groundwater levels by human activity combined with climate change in many regions illustrate the challenges of the nonrenewable nature of groundwater and the multiple dependencies of some ecosystems and agricultural systems on groundwater.77 Multiple, integrated solutions will be needed to address the impacts on the Edwards Aquifer. These will necessarily involve ways to increase supply through technological approaches, such as desalination of brackish groundwater and aquifer storage and recovery; ways to decrease demand, such as conservation and regulation; and ways to reduce the impact of urbanization through sustainable design. For example, The Edwards Aquifer Recovery Implementation Program Habitat Conservation Plan78 balances water pumping and use of the aquifer with protection of eight federally listed threatened and endangered species that depend on San Marcos Springs and Comal Springs, two of the largest springs in the southwestern United States. The plan incorporates a number of innovative water supply strategies including Aquifer Storage and Recovery and advanced water conservation, along with market-based solutions for voluntary suspension of groundwater pumping rights during drought periods.

Figure 23.7: Cross Section of Edwards Aquifer

Figure 23.7: Key characteristics of the Edwards Aquifer, such as relative shallowness and karst features, make it vulnerable to the impacts of both climate variability and climate change. Its importance as a major supplier of groundwater in central Texas makes these vulnerabilities even more pronounced. Source: Edwards Aquifer Authority.79 Used with permission.